DIAGNOSING, MANAGING, AND RESOLVING LAMENESS IN HORSES
Fig. 7. Eleven-year-old Thoroughbred Steeplechase gelding with chronic back pain with acute flare. Sonogram reveals multifidus edema and fiber disruption.
Ultrasonography was found to be a repeatable
and reliable tool for measurement of the equine epaxial muscle size.2 When examined in clinical cases of equine back pathology, there was a clear effect on the epaxial muscle size at the level of and close to areas of significant injury or pathology.2 A number of papers have focused on this MM asymmetry as it relates to other back pathology. The authors acknowledge this association, but there are also many horses with primary MM pa- thology. This paper will review a number of these findings.
5. Ultrasound Images of MM Pathology (Figs. 5–10)
Both authors claim a large amount of consulta- tions for back pain over the last 7 years and tried to evaluate the MMs on certain cases where there was a reluctant pain spasm before and after exer- cise, an absence of significant x-ray findings
around the spinous processes or epaxial joints, and a positive block when realized at the level of this spastic area. Major findings have been categorized as follows:
● Change in size and shape: This has been as- sessed mostly by doing the transactional im- ages as described already by Mc Gowan et al2. Amyotrophy unilateral or bilateral of the MMs has been considered as pathologic and poten- tially induce a loss of core. It is important to evaluate at the same level the size and surface of the longissimus dorsi muscle (LDM). The LDM does not act as a core muscle but will be part of the strength and stability of the same area.
● Change in echogenicity (hypo): This can be assessed on transactional and longitudinal views. Because of its dense pennate fiber pat-
Fig. 8. Twelve-year-old Thoroughbred Foxhunter gelding. MM cross-sectional area measurement demonstrating left-sided atrophy.
